1) Arthropods are the largest phylum, with over 900,000 species including insects, spiders, crabs, and centipedes. 2) They have segmented bodies, jointed appendages, and an exoskeleton made of chitin that must be periodically molted. 3) Digestion involves a complete digestive tract with specialized mouthparts in different groups. Respiration occurs through trachea, gills, or directly through the body surface.

1. ANIMAL KINGDOM
PHYLUM ARTHROPODA

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4. Introduction, Other features, Body wall, Digestion,
Respiration, Circulation, Excretion, Nervous system,
Reproduction
Synopsis

5. Introduction

6. INTRODUCTION
◈ Arthropod is the biggest phylum.
◈ About 9,00,000 species exist
◈ Von Siebold established phylum Arthropods.
◈ Arthropods are found in water, land, sea, in plant and
animals.
◈ Phylum includes Crabs, prawn, insets, spider, scorpion,
ticks, mite, centipedes, millipedes and fossil
arthropods which are called Trilobites.

7. Other features

8. OTHER FEATURES
◈ Body is bilateral, triplablastic with organ system level
of organisation
◈ Head is distinct [High degree of canalization],
Consists of many fused segments bears well developed
sense organ such as eyes, compound eyes, antennae.
Compound eye consist of many similar unit ommatidia
each having lens and capable of forming image.

10. OTHER FEATURES
◈ Arthropods have various shapes with externally
segmented body.
◈ Segmentation is either (1) Two region with Head and
trunk or Cephalothoras and abdomen (2) Three region
with Head, thorax & abdomen
◈ Some or all segments bear jointed appendages. Hence
name arthro - joints, poda – foot.
◈ No internal segmentation like Annelida

12. Body wall

13. BODY WALL
◈ Cuticle composed or protein & polysaccharide chitin
which is further strengthen by deposition of mineral
(calcium phosphate & carbonate)
◈ Restricts growth and periodically change during
growth known as moulting or ecdysis.
◈ Flexible part of cuticle is called suture.
◈ Chitinous plates which form exoskeleton are known as
sclerites.

14. BODY WALL
◈ Single layered epidermis without cilia & flagella.
◈ Muscle are arranged in bundles.
◈ Muscle are striped/strained - Voluntary (first time
developed in arthropods)
◈ Due to presence of joints muscle are separate in them
◈ Body cavity around viscera contain blood and is called
the haemocoel. True coelom is reduced to cavities in
reproductive organs (gonads) & excretory organs.
Coelom of gonads is called gonocoel and of nephrons is
called nephrocoel.

15. Digestion

16. DIGESTION
◈ Digestive Tract is
complete
◈ Involves 3 parts
◈ (1) Stomedaeum (Anterior)
(2) Mesenteron (Middle)
(3) Proctodeum (Posterior)
◈ Striated muscles are found
in digestive tract.

17. DIGESTION
◈ Mouth parts adapted for
◈ Biting and chewing - Biting and chewing type -
Grasshopper, Cockroach, Termites, Caterpillars.
◈ Piercing - Sucking type - Mosquitoes, Bugs
◈ Chewing lapping type - Bee
◈ Sponging type – Housefly, fruitfly
◈ Siphoning type – Butterfly, moths

18. Respiration

19. RESPIRATION
◈ Respiration is through body surface or special
structure such as gills (e.g. Prawn)
◈ Trachea (e.g. Insects)
◈ Book-lungs (e.g. Scorpion)
◈ Book-gills (e.g. King crabs)
◈ Trachea carry oxygen direct to the cells

21. Circulation

22. CIRCULATION
◈ Circulatory system is Open i.e. blood
flows in haemocoel instead of blood
vessels.
◈ Blood - With white corpuscle,
colourless – Hemolymph (e.g. Insect)
◈ Copper containing pigment
haemocyanin (e.g. Prawn)
◈ Heart - A dorsal, tubular pulsatile,
one to many chambered tubular
structure.

23. Excretion

24. EXCRETION
◈ Antennary or green glands or maxillary gland (e.g.
Crustaceans) opening directly to the exterior.
◈ Coxal gland (e.g. Arachnids)
◈ Malpighian tubules (e.g. Insects) opening into the gut.
◈ Excretory matter is Ammonia in aquatic animal, Uric
acid is land animal.

25. Nervous system

26. NERVOUS SYSTEM
◈ Nervous system comprises of a ring and a double, solid
midventral nerve cord bearing a pair of ganglia per
segment or less (Ganglia).

27. Reproduction

28. REPRODUCTION
◈ Insects communicate by Pheromones by releasing
chemical into the environment. Also acts on a sex
attraction.
◈ Sexes are separate.
◈ Fertilization internal but few aquatic has external.
◈ Gonads have ducts. Larva stage undergoes degree of
metamorphosis.
◈ Sexual dimorphism may be present.
◈ Mostly oviparous few viviparous.

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